Sudoku online

How do you play sudoku?

In sudoku, you fill a grid of 9 rows and 9 columns with the numbers 1 to 9. Each number shows up only once in each row, each column and each 3 by 3 box. Some numbers come already written and work as clues. The puzzle is solved with logic alone, with no arithmetic.

How to play

1. The grid has 9 rows, 9 columns and 9 boxes of 3 by 3. Some numbers come written in white and never change.
2. The goal is to fill every empty cell with a number from 1 to 9.
3. Each number shows up only once in each row, each column and each box.
4. Tap an empty cell, then tap a number on the on-screen keypad. On a computer, move with the arrow keys and type the number.
5. Tap the same number again to clear the cell. The eraser button clears it too.
6. Turn on Notes to write small numbers in a cell. Use notes to keep track of the candidates for each cell.
7. Made a mistake? Tap Undo to go back one move. You can go back many moves in a row.
8. Stuck? Tap Hint: the game reveals the right number for one cell and paints that number gold.
9. You win when the whole grid is filled with the right solution. Every sudoku here has a single solution.

Daily sudoku and levels

• Daily sudoku: one sudoku per level each day. It is the same for everyone, so you can compare times with family and friends.
• New sudoku: draws another grid for the chosen level, as many times as you like.
• Easy: 40 numbers come in the grid.
• Medium: 33 numbers come in the grid.
• Hard: 27 numbers come in the grid, or slightly more.
• Show mistakes: with this option on, a number that repeats in its row, column or box turns pink. With it off, you check on your own.
• The game in progress is saved on your device. Close the page and pick up later where you left off.

Tips to play better

• Start with the row, column or box that has the most numbers. Few options are left for each empty cell there.
• Pick one number and scan the grid. Tap a cell that holds it: the game highlights every copy and you see where it still fits.
• Look for the only spot: inside a box, if a number fits in just one cell, it goes there.
• Look for the only candidate: if a cell accepts just one number, write that number.
• On medium and hard, note the candidates in cells with two or three options. A matching pair of candidates in two cells removes those numbers from the other cells in the same row, column or box.
• Do not guess. Sudoku is solved with logic alone, and a wrong guess shows up much later and costs a lot.
• Stuck? Move to another part of the grid. A new number in another box often opens the way.

Frequently asked questions